Heat oven to 350 degrees. Line an 8-inch square baking pan with foil and grease the foil. Heat chocolate and butter until melted and smooth. Cool slightly and blend with sugar, baking powder, salt eggs, and vanilla in a medium bowl until well combined. Add in chocolate mixture and whisk until smooth. Stir in flour.

Spread batter evenly into pan. Bake until toothpick inserted in the center comes out mostly clean, about 20-25 minutes. Remove brownies from oven and sprinkle with white chocolate chips. You might be tempted to add more chips, since one cup doesn't seem to cover, but if you do, your brownies will be very heavily frosted. Keep this in mind. The photo below shows what an over-abundance of white chocolate chips looks like:

Let the chips sit until they are softened but not melted. Use a spatula to evenly spread the chips out over the top of the brownies, then sprinkle on the crushed peppermints.